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yaml --- r: 198832 b: refs/heads/master c: 2fd74e2 h: refs/heads/master v: v3
git-mirror · May 27, 2010 · f01ec24 · f01ec24
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diff --git a/[refs] b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 4ae9ca825e3e28441ef8155c1a81e4c14dfbf38d
+refs/heads/master: 2fd74e25df46ecb0b54700aba242dcaeb2d75f4a
diff --git a/trunk/Documentation/DMA-API-HOWTO.txt b/trunk/Documentation/DMA-API-HOWTO.txt
@@ -738,7 +738,20 @@ to "Closing".
    CONFIG_NEED_SG_DMA_LENGTH if the architecture supports IOMMUs
    (including software IOMMU).
 
-2) More to come...
+2) ARCH_KMALLOC_MINALIGN
+
+   Architectures must ensure that kmalloc'ed buffer is
+   DMA-safe. Drivers and subsystems depend on it. If an architecture
+   isn't fully DMA-coherent (i.e. hardware doesn't ensure that data in
+   the CPU cache is identical to data in main memory),
+   ARCH_KMALLOC_MINALIGN must be set so that the memory allocator
+   makes sure that kmalloc'ed buffer doesn't share a cache line with
+   the others. See arch/arm/include/asm/cache.h as an example.
+
+   Note that ARCH_KMALLOC_MINALIGN is about DMA memory alignment
+   constraints. You don't need to worry about the architecture data
+   alignment constraints (e.g. the alignment constraints about 64-bit
+   objects).
 
 			   Closing